This invention relates to an apparatus in a drill string. Specifically, this invention is a metal tube having its original diameter sufficiently reduced by the formation of non-uniform protrusions on its surface so that it may be inserted into the bore of an internally upset drill pipe. The metal tube is disposed within the drill pipe, and then expanded to conform to the inside surface of the pipe. The protrusions allow the tube to be expanded to at least its original diameter without rupturing the wall of the tube.
The idea of putting a metal tube as a liner into a drill pipe for the purpose of improving the corrosion resistance of the drill pipe and for providing a passageway for electrical conductors and fluid flow is not new. Those who are skilled in the art are directed to the following disclosures as references for installing a metal tube in a drill pipe.
U.S. Pat. No. 2,379,800, to Hare, incorporated herein by this reference, disclosed the use of a protective shield for conductors and coils running along the length of the drill pipe. The shield served to protect the conductors from abrasion that would be caused by the drilling fluid and other materials passing through the bore of the drill pipe.
U.S. Pat. No. 2,633,414, to Boivinet, incorporated herein by this reference, disclosed a liner for an autoclave having folds that allowed the liner to be installed into the autoclave. Once the liner was installed, it was expanded against the inside wall of the autoclave using hydraulic pressure.
U.S. Pat. No. 5,311,661, to Zifferer, incorporated herein by this reference, teaches a method for forming corrugations in the wall of a copper tube. The corrugations are formed by drawing or pushing the tube through a system of dies to reduce the diameter of the end portions and form the corrugations in center portion. Although the disclosure does not anticipate the use of a corrugated liner in drill pipe or other downhole component, the method of forming the corrugations is readily adaptable for that purpose.
U.S. Pat. No. 5,517,843, to Winship, incorporated herein by this reference, discloses a method of making an upset end on metal pipe. The method of the reference teaches that as the end of the metal tube is forged, i.e. upset, the wall thickness of the end of the pipe increases and inside diameter of the pipe is reduced. The upsetting process, therefore, results in an overall changing topography along the inside wall of the drill pipe.
U.S. Pat. Nos. 4,865,127; and 6,354,373 and Publication Number 2003/0178197 disclose lining a production well or a well bore. U.S. Pat. No. 5,390,742 to Dines, et al. discloses a patch for a longitudinally spaced series of tubular nipple structures installed in a well flow conductor operatively extending through a subterranean well bore. The walls of drill pipe and of production nipples require different characteristics. A drill pipe must be sufficiently strong to withstand the rotary motion and drilling strains experienced by a drill string, while the nipple comprises thinned walls such that a perforating gun may more easily rupture the wall.
U.S. application Ser. No. 10/707,232 filed by the applicants of the present invention on Nov. 29, 2003 discloses a liner insertable into the central bore of a down-hole tool which includes a resilient material rolled into a substantially cylindrical shape. The outside diameter of the liner is variable to allow the liner to be inserted into a narrowed bore of the downhole tool near the box end or pin end. Once past the narrowed bore, the outside diameter of the liner self-expands within the central bore of the downhole tool.